[Kst] Interpolation

Brisset, Nicolas nicolas.brisset at airbus.com
Tue May 13 06:33:30 UTC 2014

Hi Steve,

I tried it as well and noticed the same as Barth. Even if the plugin does not always crash, it returns NaN vectors. We need to fix the crash, but for the NaNs the best we can do is probably skip (or interpolate) them as Barth suggested.
However, I have one hint for your case where actually the sampling is different: you could use the range settings to skip every other point on reading the vector.
In the page where you select the type of plots and the ranges (after you've selected the vectors), in the upper part you could set Start to 0, and click the "Read 1 sanple per" box and set 2 frames in the spinbox right to it. Then kst skips the NaNs.


-----Ursprüngliche Nachricht-----
Von: kst-bounces at kde.org [mailto:kst-bounces at kde.org] Im Auftrag von Barth Netterfield
Gesendet: Montag, 12. Mai 2014 22:50
An: kst at kde.org
Betreff: Re: [Kst] Interpolation

Hi Steve,

Hmm.... Unfortunately, it turns out that Kst does not really support your case here :-(

The missing values are interpreted as NaNs (which seems pretty reasonable).
But the interpolation plugin does not support NaNs (and crashes).

The crashes in the existing plugins are bugs which should be fixed.  I think the fix could be done so that it would automatically be able to have them interpolate over NaNs.

So: Could you submit this as a bug so we don't forget about it?


On May 10, 2014 5:36:57 PM Steve Maher wrote:

> Hi all,
> I can't seem to perform any interpolations.   My test crashes on 2.0.7-1 on
> Ubuntu and 2.0.8rc2 on Windows 8.1.
> Attached (and below) is my (ASCII)  test case.  There are 13 values in
> vector 'a' (and INDEX, of course).  There are seven values in vectors 'b'
> and 'bi'.  Vector 'bi' contains index numbers for vector b.  Looking
> at the data you can see the intention is that vector b has values for
> every other 'a' value and bi is the index of those values relative to 'a'.
> My goal is to interpolate 'b' so that it has the same number of
> samples as 'a', then use 'b' as an X axis of a curve with 'a' as the Y axis.
> So I try interpolating with Input Vector X = bi, Input Vector Y = b,
> and Input Vector X' = INDEX.  This crashes no matter which
> interpolation plugin I use.
> Seeing NaN's when looking at the 'b' and 'bi' vectors may be an issue.
>  However, I'm assuming since there are interpolation plugins there
> must be SOME way to have vectors of varying lengths.
> I must be missing something.
> Thanks for any tips,
> Steve
> a b bi
> 112.5 428 0
> 187.5
> 262.5 345 2
> 337.5
> 412.5 119 4
> 487.5
> 567.5 162 6
> 637.5
> 712.5 211 8
> 787.5
> 862.5 292 10
> 937.5
> 100.5 623 12

Barth Netterfield
University of Toronto
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